| Ambiance Additions | Margaret Elizabeth Donnelly | sales@ambianceadditions.com | (714) 871 4165 | GC, remodel, ADU | Fullerton · Orange County | — | — |
| Ambiance Painting INC | Jorge Alberto Ramirez | — | (714) 725 4847 | Windows, patio, painters | Orange · Orange County | — | — |
| Ambient Environmental INC | Robert John Valousky | — | (951) 272 4730 | Other | Anaheim · Orange County | — | — |
| Ambiente Construction & Design Corp | Morales Nazario | — | (323) 321 9074 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Ambriz General Construction | Alejandro Gutierrez Ambriz | — | (951) 604 8224 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| Amburgey/carich Construction INC | Ronald Joseph Amburgey | — | (949) 548 7001 | Other | Costa Mesa · Orange County | — | — |
| Amc Cabinetry | Mc Namara Anthony | — | (714) 258 6897 | Other | Anaheim · Orange County | — | — |
| Amc Electric Services INC | Magana Cristobal Magana | cristobal@amcelectricservices.com | (562) 844 2285 | Electricians | La Habra · Orange County | — | — |
| Amco Development | Amco Development | — | (714) 707 1472 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Amd Stone Touch INC | Albert Manuel Chavez | — | (714) 718 3664 | Other | Stanton · Orange County | — | — |
| Amended Spaces INC | Michael Gene Schmidt | — | (714) 423 9719 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| Amendt Stair Framing | Amendt Stair Framing | — | (714) 454 4334 | Other | Santa Ana · Orange County | — | — |
| Ameri-cal Repipe And Plumbing INC | William Vannarath | — | (714) 694 5954 | Electricians | Buena Park · Orange County | — | — |
| Ameri-cal Roofing INC | Austin James Petrush | — | (657) 238 7873 | Other roofers | Los Alamitos · Orange County | — | — |
| America Alarm LLC | Robert Khoi Bui | — | (949) 992 6868 | Electricians | Westminster · Orange County | — | — |
| America Build | America Build | — | (714) 805 4094 | GC, remodel, ADU | Yorba Linda · Orange County | — | — |
| America Pro Design INC | Peter Michael O'boyle | — | (714) 872 1958 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| America's Finest Building & Repair | America's Finest Building & Repair | — | (714) 484 3463 | GC, remodel, ADU | Cypress · Orange County | — | — |
| America's Instant Signs | Dipali Nanda | — | (714) 693 2989 | Other | Anaheim · Orange County | — | — |
| Americal Construction Management Group Corp | Allen Monshietehadi | — | (949) 297 4621 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| American Air Balance Co LLC | Deborah Kay Bonura | info@aabctab.com | (714) 693 3700 | HVAC | Anaheim · Orange County | — | — |
| American Air Plus | American Air Plus | — | (949) 939 1851 | HVAC | Rancho Santa Margarita · Orange County | — | — |
| American Alarm Systems INC | Milton Gary Beale | — | (714) 547 7474 | Electricians | Santa Ana · Orange County | — | — |
| American Ashlar Corporation | Nikbakht Kamran Nouri | — | (949) 795 6706 | GC, remodel, ADU | Irvine · Orange County | — | — |
| American Asphalt And Striping INC | Michael Lawrence Inzano | — | (949) 361 8687 | Other | San Clemente · Orange County | — | — |
| American Assets General Construction | Mario Rene Velasquez | — | (714) 745 9085 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| American Best Construction INC | Tony Hyosik Kim | — | (949) 272 6662 | Other roofers | Irvine · Orange County | — | — |
| American Best Remodeling INC | Cesar Ventura Munoz Munoz | — | (714) 341 5261 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| American Builder | American Builder | — | (310) 614 2882 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| American Castles | American Castles | — | (800) 924 9630 | Electricians | Garden Grove · Orange County | — | — |
| American Coastline Construction | Peter Marshall Zazzara | — | (714) 653 4005 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| American Comfort Air INC | Ryan Allen Keli'i Hall | — | (951) 965 1151 | HVAC | Yorba Linda · Orange County | — | — |
| American Communication Solutions INC | Brian Edward Johnson | — | (714) 998 7772 | Other | Anaheim · Orange County | — | — |
| American Continental Engineering Corp | Dong Hak Lee | — | (213) 393 5032 | HVAC | Garden Grove · Orange County | — | — |
| American Contractors INC | Kathleen Wiggam | — | (714) 282 5700 | Other | Orange · Orange County | — | — |
| American Cooling Tower INC | Erik August Johnson | — | (714) 898 2436 | HVAC | Santa Ana · Orange County | — | — |
| American Cpl INC | Carl Peter Ludwig | — | (714) 300 8114 | Other | Yorba Linda · Orange County | — | — |
| American Crematory Equipment Co | Donald Lewis Ridgeway | — | (562) 926 2876 | Other | Cypress · Orange County | — | — |
| American Development Construction INC | George Luis Gomez | — | (714) 296 8431 | GC, remodel, ADU | Fullerton · Orange County | — | — |
| American Disaster Cleaning Group INC | Michael Douglas Jensen | — | (951) 970 0240 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |